Track-type machines are used in a wide variety of rugged service environments. The use of ground engaging tracks rather than wheels can provide enhanced traction, stability, and robustness to a machine system over what might otherwise be available. A typical undercarriage system in a track-type machine includes a plurality of track shoes coupled together in an endless track chain by way of a set of track links, and extending about a drive sprocket and one or more rotatable idlers. The track assembly provides better mobility on uneven ground and typically renders excellent traction while spreading the weight of the machine over a large area. Mining, construction, landfills, forestry, and still other service environments are notable examples of where track-type machines are advantageously used.
During operation, the movement of the track-type machine typically causes the track assemblies to pick up dirt and debris or any outlying material as it makes contact with the ground, only to have the material deposited on the track frame and subsequently on the other components of the track-type machine. In these environments, and particularly in landfills, abrasive materials are present at most worksites where track-type machines are used. This may result in an increased machine weight, more friction forces between the moving components in the track assemblies and increased machine wear. Wear is generally caused as the accumulated material results in an abrasive action on the components of the machine.
One area where such accumulation occurs is in the seal cavities of rotating components such as carrier rollers, track rollers, idler rollers, sprockets and the like, all of which may be encompassed by the term “roller” as used herein. As one example, carrier rollers extend above the track frame and support the track chain between the sprocket and an idler roller to prevent slack in or sagging of the track chain. Carrier rollers are typically supported by a carrier stand extending from the track frame and an axle or shaft extending from the carrier stand. Oil, grease or other lubricants disposed in a space between a carrier roller and its shaft reduce friction between the components. Annular or toroidal seals, such as O-rings, may be used to retain the lubricant in the space, but a seal cavity may place the seals in fluid communication with the ambient atmosphere surrounding the carrier roller. When operating in the environments described above, abrasive material may accumulate in the seal cavity and eventually displace the seal or abrade the seal resulting in the loss of lubricant and ultimate failure of the carrier roller. In some environments, refuse such as trash bags and other plastic bags, wire, video cassette tape and the like can enter the cavity wrap around the seals. In view of these situations, a need exists for an improved configuration of the track carrier roller that prevents or, at a minimum, retards the accumulation of abrasive material in the seal cavity of the roller.